Fluid pressure brake



Dec. 22, 1935. s G, DOWN 2,065,214

FLUID PRESSURE BRAKE Filed OCL. 4, 1935 ATTORNEY Patented Dec. 22, 1936 UNE TE D fSfT S "PATENT @Ff-'ICE lFLUID PRESSURE BRAKE 4Sidney G. -DownEdgewood, Pa., assigner to The Westinghouse AirfBrake Company, Wilmerding, Pa., a corporation of Pennsylvania `Application October 4, 1935, Serial No. 43,519

, 6 Claims.

is reducedfor a period ioftime suilcient toinsure that the brakes will Jbe. applied on allof'the cars yof 4the train beforethebrakes have been applied on the cars at the head end of the train-'with such 'rforce in Vadvance of Vthe brakes von' vthe carsat the rearendvof thetrain as to resultin arunning linxoffthe slackV intheitrain at such a ratethat excessivefshocks"willbeproduced After this rbrakei cylinder buildup delayperiod, 'andfafter Vthe slack' hasrunin the rate rvof supply ofrfluid 'in' the'. brake cylinder is increased so that the a pressureio the fluidy in the brake -cylinder builds up at a rapid rate.

e. A2 fluid pressure :brake 'equipment having i' the above feature', by wlnchrin'an 'emergency applicationtof the brakes :there Vis aninitial-inshot 1ofluidunder#pressure to lthe brake cylinder, followed by aslow'build up y'of brake cylinder "pressure'to the" brakecylincler, is disclosed in the United States yPatent No. 2,031,213 to Clyde C. Farmer.

In the brake 4equipment shownin the above -identiedpatent a restriction inthe rate of flow of ruid lto the `brake cylinder is produced by 'valve' means, which-.during an emergencyapplircaticn'of the brakes; is controlledbyian abutment subject to the Vpressureof the fluid supplied-tothe brake cylinder', and which operates on a predetermined increase in the pressureV of the fluid supplied to the brake cylinder to close the passage controlled V:by said valve'means, and' thus reduce the .ratezof lflow of huid to the brake cylinder.

In addition, in the equipment shown'in the above-identied patent the increase in the rate of flow of iiuid to the brake cylinder following the brake cylinder buildeup delay-'period is produced 'by vvalve means controlled by theopposing pressures of :the huid supplied ito. thebrake cylinder `and the 'pressure of the fluid in the slide valve cham-berof .the emergency-portion -of the valve d'evice, 'and Awhich operates on an increase in the pressurepf the iluid inthe `brake'cylinder maintained inoperative until the pressure of the.

to open a communication through which iiud may be supplied to the bra-ke cylinder.

It has `been found that it may be desirable in Some classes of service, such as in relatively short trains where the run in of slack isless serious 5 than in long trains, to eliminate the brake cylinder build-up delay period.

It is the principal object of my invention to provide a brake controlling valve device having meansadapted to restrict the rate of flow of fluid 110 to the brake cylinder following an increase in the pressure of the fluid in the brake cylinderto a l predetermined value, together with optionally opr-erable means for rendering the last named means inoperative.

1A further object of the inventionis to provide a brake controlling valve device havingmeans subject to and operated upon a predetermined increase in the pressure of the fluid supplied to Ythe-brake cylinder for reducing the rate of' ow 0 of uid to the brake cylinder, together with optionally operablemeans for rendering said means inoperative.

Another object of the invention is to provide a brake controlling Valve device having means subject to and operated upon a predetermined increasein the pressure of the fluid supplied to the brake cylinder for reducing the rate of ow .of uid to the brake cylinder, other valve 1 means subject to the pressure of iluid supplied to the brake cylinder and normally operated upon an increasev in said pressure to a higher predetermined Vpressure to open a communication through which uid may be supplied tothe brake cylinder, whereby fluid will thereafter. be 35 supplied to the brake cylinder at a more rapid rate, and having means to optionally vary the pressureto which the first-named valve means is responsive, whereby said valve means may be '40 uicl supplied to the brake cylinder increases to a value sufcient to effect operation of the other of Saidvalve means to open the communication controlled thereby.

Other objects of the invention and features ofl 45 `novelty Will be apparent from the following de- .,scription taken in connection with the accoml panying drawing, in which- Fig. 1 is a diagrammatic View of a fluid pressure brake equipment for a car, including a brake. 50 controlling valve 'device shown in section and em- #bodying my invention,

VFig. 2 is a fragmentary sectional View taken substantially along the line 2 2 of Fig. 1, and

tion of the brake controlling valve device shown in Fig. 1 with the parts shown in a different position than thatI in which they are shown in Fig. 1.

As shown in the drawing the brake controlling Valve device, which is indicated generally by the reference numeral may comprise a pipe bracket section 2, to which is secured a triple valve casing 3, and an emergency valve casing 4. The brake pipe 6 is connected to a passage 1 in the pipe bracket section 2, a brake cylinder 8 is connected by a pipe 9 to a passage i9 in the pipe bracket section 2, an auxiliary reservoir l2 is connected by a pipe I4 to a passage i5, and an emergency reservoir I1 is connected by a pipe I8 to a passage I9.

'I'he triple valve casing 3 has a Apiston chamber 2| formed therein and this chamber is connected to the brake pipe passage 1 and contains a piston 23. On the opposite side of the piston 23 is a Valve chamber 25, which is connected to the auxiliary reservoir passage I5, and which contains a main slide valve 21, and an auxiliary slide valve 28 adapted to be operated by the piston 23 through a piston stem 39.

The emergency valve portion, indicated generally by the reference numeral 4, includes a quick action vent valve device indicated generally by the reference numeral 33, an inshot valve device indicated generally at 35, and a timing valve device indicated generally by the reference character 36.

The emergency valve portion comprises a piston 49 having a piston chamber 4I at one side thereof connected to the b-rake pipe passage 1, and having on the opposite side a valve chamber 43 connected by way of a passage 44 with a quick action chamber 45.

The valve chamber 43 contains a main slide valve 41 and an auxiliary slide valve 48 adapted to be operated by the piston 49 through the piston stem 49.

The vent valve device, indicated generally at 33, comprises a piston 59 having a piston chamber 5I on one side thereof connected to a passage 53 leading to a port in the seat of the slide valve 41. A vent valve 56 contained in the valve chamber 51 is adapted to be operated by the piston 59 through the piston stem 59.

The inshot valve, indicated generally by the reference character 35, comprises a valve element 6I which is mounted in a chamber 62 and is normally urged into engagement with a seat rib 64 by means of a spring 65 so as to cut off communication between the chamber 62 and a. chamber 66 by way of a passage 61. The chamber 62 is constantly connected with the chamber 66 by way of a restricted passage 68.

The inshot valve device 35 also includes a movable abutment 19 having a sealing gasket 1I associated therewith and provided with a seat rib adapted to seat upon a seat formed on the casing 4, said seat surrounding a chamber 12 which is constantly connected with the chamber 96, and also with the brake cylinder passage I9 by way of a passage 14.

The abutment 10 has a stem 15 associated therewith and adapted to operate the valve 6I, the stem being of such length as to hold the valve 6I away from the seat rib 64 when the sealing gasket 1I is in engagement with the seat formed on the casing 4.

'Ihe movable abutment 19 has a spring 11 associated therewith and normally urging the abutment to the position in which the sealing gasket 1I engages the face of the casing 4, The spring 11 is proportioned so as to exert a greater force on the abutment 19 and the stem 15 than the force exerted by the spring 65 on the valve 6|, so that the valve 9| will normally be moved away from the seat rib 64 by the spring 11.

One end of the spring 11 engages a face of a plunger 89 which is mounted in a bore in the casing cover plate 9|, and has an enlarged head 82, which engages one face of a exible diaphragm 84 which is clamped between the casing cover section 8| and a casing section 95.

The head portion 92 in one position of the plunger 89 is adapted to engage the casing cover section 8| to limit movement of the plunger 89 to the right, as viewed in Fig. 1 of the drawing.

'Ihe other face of the diaphragm 84 is engaged by a plunger 81 which is mounted in a bore in the casing section 85 and which is provided with an enlarged head portion 89 which engages a portion of the casing section 85 to limit movement of the plunger to the left, asvviewed in Fig. 1 of the drawing.

In the brake equipment provided by this invention manually or optionally operated means is provided to move the plungers 89 and 81 from the position in which the head 89 on the plunger 81 is in engagement with the casing section 85, which is the position in which these members are shown in Fig. 1 of the drawing, to the position in which the head 82 of the plunger 80 is substantially in engagement with the casing cover section 8|, which is the position in which the plungers are shown in Fig. 3 of the drawing.

The manually or optionally operated means comprises a lever, indicated generally by the reference character 99, and having adjacent opposite ends thereof shaft portions 9| which are rotatably supported by means of spaced brackets 93 which may be secured in any suitable manner, not shown, to the car structure. The ends 95 of the lever 99 extend substantially perpendicularly to the shaft portions 9|, and the lever is preferably of such length, and is arranged on a car so that one end 95 is located on one side of the car, while the other end 95 is located on-the other side of the car.

'I'he lever 99 has formed thereon intermediate its ends an off-set portion 91 having a rotor 98 rotatably supported thereon and positioned in a recess 99 in the casing section 85 surrounding the exposed end of the plunger 81.

The brackets 93 are preferably arranged so that the axis on which the shaft portion 9| of the lever 99 pivots is disposed substantially in alignment with the center line of the plungers 91 and 89, while the portion of the casing section 85 surrounding the recess 99 is adapted to limit the range of movement of the rotor 98 aboveV and below the plane of the shaft portion 9| of the lever 99, and is arranged so as to permit the rotor 98 to move above this plane a somewhat greater distance than it is permitted to move below this plane.

The timing valve device 36 comprises a flexible diaphragm |92, which is subject on one side to the pressure of the fluid in a chamber |93 which is connected with the slide valve chamber 43 by way of a passage |94.

A valve |98 is positioned in a chamber III on the opposite side of the diaphragm |92, and is normally held in engagement with a seat rib |98 surrounding the end of a passage I I9 so as to eut off communication between the passage II9 and the chamber III in which the valve |96 is mounted, and which is in constant communicafluid flows from the piston chamber tion with the brake cylinder of a restricted passage II4.-

In operation the brake pipe 6 is supplied with uid under pressure and fluid flows therefrom through the passage l to the piston chamber 2|, moving the piston 23 to the release position, if it is not already in thatl position, Which is the position in which it is shown in the drawing, whereupon iiuid under pressure hows from the piston chamber 2| byway of the feed groove |26 to the valve chamber 25, and thence by Way of the passage I5 and the pipe I4 to the auxiliary reservoir I2, charging this reservoir with iluid at the pressure carried in the brake pipe 6.

When the piston 23 is moved to the release position the slide valve 2 is moved to a position in which a port |22 in the slide valve registers with the end of the emergency reservoir passage i9, while the port I 22'in the slide valve is uncovered by the auxiliary valve 28 so that fluid under pressure is supplied from the valve chamber 25 to charge the emergency reservoir I1 with fluid at the pressure carried in the brake pipe.

In the release position of the piston 23 the brake cylinder 8 is connected to the atmosphere through the pipe 9, passage |I3, passage '54, the chamber 65, past the open inshot valve 6I to the chamber 62 and to the passage |25, and through a cavity |26 in the slide valve 2 to the atmospheric exhaust passage I 28.

Fluid under pressure also flows from the brake pipe 6 and the passage 'I to the piston chamber 4| of the emergency portion 4, and with the piston 40 in the release position as shown in the drawing, 4| through the'port |30 to the passage 44 and thence to the quick action chamber 45 and to the emergency slide valve chamber 43.

If it is desired to eect a service application of the brakes a gradual reduction in the brake pipe pressure is made and theftriple valve piston 23 is thereby shifted from the release position, thus moving the graduating valve 23 to uncover a service port |35 in the slide valve 27|, and to close the port |22. The main slide valve 2'! is then moved by the piston 23 until the service port |35 registers with the passage |25.

Fluid under pressure is then supplied to the passage |25 through which it ows to the chamber $2 of the inshot valve device 35, and then past the open inshot valve 6I through the passage 61 to the chamber 66, and through the passage 'I4 to the passage Ill to which is connected the pipe 9 leading to the brake cylinder.

The chamber I3 on the spring side of the abutment i is connected by a passage |38 with an inshot piston volume |40, which is connected with a port in the seat of the slide valve 4'! by way of a passage I4 I In the release position of the slide valve 47 a cavity |43 in the slide valve connects the passage |4| With a passage |46, Which is connected to the passage II il, which leads from the passage |25, so that when fluid under pressure is supplied to the passage I 25, and thereby to the brake cylinder 8 in a service application of the brakes, uid is also supplied from the passage |25 by way of the passage I I0, the passage |46, the cavity |43, the passage I 4I the volume |46, and the passage |38 to the chamber 78 on the spring side of the abutment 16.

During a service application of the brakes, therefore, the pressure of the uid on opposite sides of the abutment 'Ill will be substantially equal, and the spring 'I1 will operate to maintain the abutment l in the position in which the sealpassage I0 by way ing gasket 'II is in engagement With the casing 4, and in which position of the abutment 'I6 the valve 6| is maintained away from its seat by the stem '15.

Upon a gradual service rate of reduction in the brakev pipe pressure the emergency piston 46 is moved so as to shift the auxiliary valve 48 to a position in which a port |5| in the auxiliary valve 43 registers with a port |52 in the main slide valve 4?, which port registers With an atmospheric exhaust port |54 in the casing 4. The rate at which iiuidv under pressure in the valve chamber 43, and in the quick action chamber 45 is reduced by flow of fluid through the port |5| is equal to the rate at which the brake pipe pressure is reduced in eiecting a service application, so that if the rate of reduction in brake pipe pressure does not exceed the service rate the piston 40 will not be operated to shift the main slide valve 4l to the emergency application position.

When the brake pipe pressure is increased to eiect a release of the brakes the triple valve piston 23 is shifted to the release position, in which position the feed groove is opened to permit the re-oharge of the auxiliary reservoir I2 from the brake pipe, and in which the brake cylinder 3 is connected to the atmosphere through the cavity as hereinbefore described.

In addition, when the triple valve piston 23 is shifted to the release position as a result of an increase in the pressure of the iiuid in the brake pipe, the chamber 'I8 on the spring side of the abutment 'I0 is vented to the atmosphere by way of pasasge |38, volume |40, passage |4I, cavity 43 in the slide valve 41, passage |46, passage I, passage |25, cavity |26` in the slide valve 2 and the passage |28.

Upon a sudden emergency rate of reduction in brake pipe pressure the triple valve piston 23 is shifted to the application position as in a service application of the brakes, so that fluid under pressure is supplied from the auxiliary reservoir l2 to the brake cylinder 8 as hereinbefore described.

The emergency piston 46 is moved on a sudden reduction in brake pipe pressure so that the auxiliary slide valve 48 is shifted to a position in which the port |56 tlnough the slide valve 4l, and which registers with the passage 53 is uncovered by the end of the auxiliary slide valve 48. Fluid under pressure is then supplied from the valve chamber 43 and the quick action chamber 45 through the passage 53 to the piston chamber 5I. The quick action piston 53 is thereupon actuated to eicct the unseating of the vent valve 56 so that fluid is Vented from the brake pipe to the atmosphere by Way of the passage '1, the chamber 57 and past the unseated valve 56 to the atmosphere, and as a result of this reduction in brake pipe pressure the emergency piston 4S then moves to the emergency position and moves the main slide valve 4i en its seat.

En the emergency position of the slide valve 4l, the cavity 43 connects the passage I9, leading .from the emergency reservoir Il, with the passage i46, which connects with the passage I0, which is connected by way of th-e passage |25 with the chamber S2 of the inshot valve 35. In this position, the slide valve 4'I cuts ofi communicatic-n through the passage |4| so as to cut oi the flew of fluid to the inshot piston volume |45 and to the chamber '18 on the spring side of the movable abutment 10, so that the chamber le remains at atmospheric pressure.

On an emergency application of the brakes fluid under pressure is supplied to the chamber 62 of the inshot valve 35 from both the auxiliary and emergency reservoirs, and fluid flows from this chamber to the brake cylinder by way of the passage 61, and also by way of the retricted passage 68 which lead to the chamber 66, whichv is in constant communication with the brake cylinder 8 by way of the passage 14 and the passage I0. The rate of flow of fluid to the brake cylinder at this time is determined by the capacity of the passages 61 and 68.

When the pressure of the fluid supplied to the brake cylinder in an emergency application of the brakes has increased to a degree such that the uid under pressure in the chamber 12, which is constantly connected to the chamber B, increases to a predetermined value which is su'icient to overcome the pressure of the spring 11 on the opposite side of the abutment 19, assuming that the lever 99 is in the position in which it is shown in Fig. 1 of the drawing, the abutment 19 will be moved to the left against' the spring 'l1 until the seat rib 19 engages the sealing gasket 16 secured between the casing cover lsection 8| and the body li. When the abutment 'I0 moves to this position the stem 15 moves away from the valve 6l and this valve is moved into engagement with the seat rib 665 by the spring 65, thus cutting off the flow of fluid to the brake cylinder byway of the passage 91. This effects a reduction in the rate of flow of uid from the chamber 62 to the brake cylinder, as fluid thereafter is supplied to the brake cylinder from the chamber 62 only by way of the restricted passage 68.

In an emergency application fluid under pressure supplied from the slide valve chamber 43 to the piston chamber 5| of the vent valve device 33 is gradually vented to the atmosphere by way of a restricted port |69 through the piston 5D so that the pressure of the uid in the valve chamber t3 and in the quick action chamber 45 is gradually reduced.

The uid from the slide valve chamber 43 also is present in the chamber |03 of the timing valve device 3S, while the pressure of the fluid supplied to the brake cylinder acts on the valve |06 on the opposite side of the diaphragm |92. As a consequence, after a period of time, when the increase in brake cylinder pressure in the passage H9 is suicient to overcome the reducing quick action chamber pressure in the chamber |93, the diaphragm |62 will be shifted to the left so as to permit the valve |955 to move away from the seat rib B98, thus opening communication from the passage H9 to the chamber i, and thus by way of the choke or restricted passage I4 to the passage I9 which leads to the brake cylinder. This results in an increase in the rate of supply of iluid under pressure to the brake cylinder 8.

The brake controlling valve device provided by this invention may be controlled, if desired, so as to eliminate the brake cylinder build up delay period. In order to condition the device for this method of operation the lever 99 is rotated in a clockwise direction, as viewed in the drawing, from the position in which it is shown in Fig. 1, to the position in which it is shown in Fig. 3.

During rotation of the lever 9!) from the position in which it is shown in Fig. 1 to a point at which the rotor 99 is substantially in the plane of the axis of the lever 99 and the center line of the plungers 91 and 8i), the plunger 9'! is moved to the right, and its movement is transmitted through the diaphragm 89 to the plunger 80, thus moving this plunger to the right and increasing the degree of compression of the spring Ti, and thereby the force exerted by the spring on the movable abutment 10, tending to hold this abutment in the position in which the rib on the sealing gasket 'll engages the casing 4, and in which the stem l5 associated with the abutment 1|) maintains the valve 6I out of engagement with the seat rib 6d.

On further rotation of the lever the plungers 81 and 8d will be permitted to recede slightly, and when the lever 99 is moved to a position in which the rotor 98 engages the lower face of the Wall surrounding the cavity 99 it will be held in this position by the spring 'l1 acting through the plungers 8|) and 8l, thus preventing the unintended return of the lever to the position in which it is shown in Fig. 1 of the drawing.

With the lever 99 in the position in which it is shown in Fig. 3 of the drawing, on a sudden emergency rate of reduction in brake pipe pressure the triple valve piston 23 and the emergency piston Il!! will be shifted to the application position as described above, and uid under pressure will be supplied from the auxiliary reservoir l2 and the emergency reservoir ll' to the chamber E2 in the inshot valve 35. Fluid will thereupon be supplied from the chamber 62 to the brake cylinder 8 by way of the passage 6l and the restricted passage 98 which communicate with the chamber 56. Fluid under pressure will also be supplied from the chamber 66 to the chamber if: onthe right hand face of the abutment T0, but because of the increased force exerted on this abutment by the spring ll and opposing its movement by fluid under pressure in the chamber l2, the abutment will not be moved, but will remain in the position in which it is shown and will maintain the valve 6| away from the seat 94. Fluid will, therefore, continue to be supplied to the brake cylinder at the same rate as it was initially supplied to the brake cylinder.

In a preferred construction, when the lever 90 is moved to the position in which it is shown in Fig. 3 of the drawing, the degree of compression of the spring 'l'l is increased sufficiently so that the abutment 'i9 will not be moved by fluid under pressure in the chamber 'l2 of a value less than that which is normally operative to eiect unseating of the valve |96, and the degree of compression or the spring T! and may be increased to such a value as to maintain the abutment 'i9 in the position in which it is shown in Fig. 1 of the drawing even when pressure of the fluid supplied to the brake cylinder is at a maximum.

The brake controlling valve device provided by this invention may be restored to normal operation when desired, by rotating the lever 99 in a counterclockwise direction from the position in which it is shown in Fig. 3, tothe position in which it is shown in Fig. 1 of the drawing. This permits the plungers 99 and 81 to move to the left until the head 39 on the plunger 8'! engages the casing section 85, thereby reducing the degree of compression of the spring l1.

From the foregoing it will be seen that the bra-ke equipment provided by my invention has optionally operable means for cutting out the inshot valve during an emergency application of the brakes so that this valve is not effective to produce a restriction in the rate of fluid to the brake cylinder.

While one embodiment of the invention has been illustrated and described in detail, it should be understood that the invention is not limited to these details of construction, and that numerous modifications and changes may be made without department from the scope of the following claims.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

l. In a fluid pressure brake, in combination, a brake pipe, a brake cylinder, a brake controlling Valve device operated upon a reduction in brake pipe pressure for supplying iluid under pressure to the brake cylinder, valve means controlling a communication through which uid under pressure is supplied toI the brake cylinder, control means subject to the opposing pressures of the iluid supplied to the brake cylinder and of a spring and controlling said valve means, and means to adjustably vary the pressure exerted on said means by said spring, said control means being adapted in response to a predetermined increase in the pressure of the fluid supplied to the brake cylinder in one adjustment of the spring to operate the valve means to effect a reduction in the rate of flow of iluid to the brake cylinder, and being adapted in another adjustment of the spring to be inoperative in response to said predetermined increase in the pressure of the uid supplied to the brake cylinder to 0perate the valve means to effect a reduction in the rate of loW of fluid to the brake cylinder.

2. In a fluid pressure brake, in combination, a brake pipe, a brake cylinder, a brake controlling valve device operated upon a reduction in brake pipe pressure for supplying fluid under pressure to the brake cylinder, valve means controlling a communication through which fluid under pressure is supplied to the brake cylinder, means subject to and operated upon a predetermined increase in the pressure of the fluid supplied to the brake cylinder for operating said valve means to effect a reduction in the rate of flow of lluid to the brake cylinder by way of said communication, other valve means controlling a communication through which fluid under pressure is supplied to the brake cylinder, means normally operated upon a higher predetermined increase in the pressure of the uid in the brake cylinder for operating said valve means to permit the supply of iluid to the brake cylinder by way of said communication, and optionally operable means to render the first named valve means ineiective to reduce the rate of ow of luid to the brake cylinder.

3. In a fluid pressure brake, in combination, a brake pipe, a brake cylinder, a brake controlling valve device operated upon a reduction in brake pipe pressure for supplying fluid under pressure to the brake cylinder, valve means controlling a communication through which iluid under pressure is supplied to the brake cylinder, means subject to and operated upon a predetermined increase in the pressure of the luid supplied to the brake cylinder for operating said valvemeans to eiect a reduction in the rate of iloW of iluid to the brake cylinder by Way of said communication, other valve means controlling a communication through which iluid under pressure is supplied to the brake cylinder, means normally operated upon a higher predetermined increase in the pressure of the liuid in the brake cylinder for operating said other valve means to permit the supply of uid to the brake cylinder by Way of said communication, and optionally operable means to render the iluid pressure operated means associated with the rst named valve means ineiective to operate said valve means to eiect a reduction in the rate of flow of fluid to the brake cylinder.

4. In a iluid pressure brake, in combination, a brake pipe, a brake cylinder, a brake controlling Valve device operated upon a reduction in brake pipe pressure for supplying fluid under pressure to the brake cylinder, valve means controlling a communication through which iiuid under pressure is supplied to the brake cylinder, means subject to and operated upon a predetermined increase in the pressure of the fluid supplied to the brake cylinder for operating said valve means to effect a reduction in the rate of flow of fluid to the brake cylinder by way of said communication, other valve means controlling a communication through which iluid under pressure is supplied to the brake cylinder, means normally operated upon a higher predetermined increase in the pressure of the fluid in the brake cylinder for operating said other valve means to permit the supply of fluid to the brake cylinder by Way of said communication, and optionally operable means to render the fluid pressure operated means associated with the first named valve means ineffective to operate said valve means to effect a reduction in the rate of flow of fluid to the brake cylinder in response to uid pressures less than that normally operative to operate the uid pressure operated means associated with the second named valve means to operate said Valve means to permit the ow of fluid to the brake cylinder.

5. In a fluid pressure brake, in combination, a brake cylinder, a brake controlling valve device operative to supply iluid under pressure to the brake cylinder, a valve for controlling a communication through which said brake controlling valve device supplies uid to the brake cylinder, a spring. a movable abutment subject to the opposing pressures of the brake cylinder and said spring for normally holding said valve in open position and operated upon an increase in brake cylinder pressure sufficient to overpower the pressure of the spring to effect the closure of said valve, and manually controlled means for varying the pressure of the spring on said abutment.

6. In a fluid pressure brake, in combination a brake cylinder, a brake controlling valve device for controlling the supply of iluid under pressure to the brake cylinder, a spring, a valve device subject to the opposing pressures of the brake cylinder and said spring for controlling a cornmunication through which said brake controlling valve device supplies fluid to the brake cylinder. and manually controlled means for varying the pressure of said spring on said abutment comprising a movable member engaging said spring, a rotatable element including an arm, and a roller carried by said arm and engaging said member, whereby the rotation of said arm causes the roller to move said member so as to increase the compressive force of the spring on said abutment.

SIDNEY G. DOWN. 

